This is the setup I am using to publish events for my Brink Flair 300 heat recovery unit. I have a Raspberry Pi 3, with an RS485>USB, connected to the 2 & 3 pin of the X15 input of the HRU. The flow in Node-Red talks locally to the device via modbus, and then connects to an mqtt server that is used for further connection to Home Assistant, this appears to be the most robust solution.
I used this USB stick: Rpi RS485 USB, but I think any of them will work. You do not need to buy the super expensive 'digital adapter' and the app, and with this setup you also do not need the super expensive RF bridge and connectors (though will likely want some physical alternative to this setup to turn it on / off if needed).
It currently provides temperature, set fan speed, actual fan speed, binary sensors for max, medium, normal (same as the 4-way RF switch) and inputs for speed (50-300, +50, -50). I also have another flow connecting this to the output of my air sensor, so when the air quality drops or it detects us cooking it turns the ventilation on!
Huge thanks to https://github.com/sirjackal/brink-modbus as this was essential in making it all work and getting the steer towards Modbus being the way to connect.
Use the 2 & 3 connections to the red X15 (note that mine came with a removable red plug already in it - so I just needed to connect it).
sensor:
- platform: mqtt
unique_id: "ventilation/supply_temperature"
name: "Ventilation Supply Temperature"
state_topic: "ventilation/supply_temperature"
unit_of_measurement: "°C"
value_template: "{{ value }}"
- platform: mqtt
unique_id: "ventilation/outside_temperature"
name: "Ventilation Outside Temperature"
state_topic: "ventilation/outside_temperature"
unit_of_measurement: "°C"
value_template: "{{ value }}"
- platform: mqtt
unique_id: "ventilation/flow_speed"
name: "Ventilation Flow Speed"
state_topic: "ventilation/flow_speed"
unit_of_measurement: "m3"
value_template: "{{ value }}"
- platform: mqtt
unique_id: "ventilation/set_flow_speed"
name: "Ventilation Set Flow Speed"
state_topic: "ventilation/set_flow_speed"
unit_of_measurement: "m3"
value_template: "{{ value }}"
binary_sensor:
- platform: mqtt
unique_id: "ventilation/speed_normal"
name: "Ventilation Normal Speed"
payload_on: "on"
payload_off: "off"
state_topic: "ventilation/speed_normal"
value_template: "{{ value_json.payload }}"
- platform: mqtt
unique_id: "ventilation/speed_medium"
name: "Ventilation Medium Speed"
payload_on: "on"
payload_off: "off"
state_topic: "ventilation/speed_medium"
value_template: "{{ value_json.payload }}"
- platform: mqtt
unique_id: "ventilation/speed_max"
name: "Ventilation Max Speed"
payload_on: "on"
payload_off: "off"
state_topic: "ventilation/speed_max"
value_template: "{{ value_json.payload }}"
switch:
- platform: mqtt
unique_id: fan_max_switch
name: "Ventilation"
state_topic: "ventilation/speed_max"
command_topic: "ventilation/air_flow"
payload_on: 300
payload_off: 50
state_on: "on"
state_off: "off"
optimistic: false
qos: 0
retain: true
